JP2003021201A - Automatic transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic transmission of a simple structure and capable of manufacturing at a low cost by operating one of friction elements as a start clutch. SOLUTION: In the automatic transmission 1 forming a multi-gear shaft by combining a first gear train 3 including a simple planetary mechanism 3a and forming a two-stage gear shift and a second gear train including a forward clutch C1 and a reverse clutch C2 and forming a three-stage or more stage gear shift, a hydraulic control circuit 11 operating either of a clutch C0 or a brake B0 provided on the first gear train 3 as the start clutch is provided.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-speed automatic transmission mounted on a vehicle, and more particularly to an automatic transmission employing a friction start system. 2. Description of the Related Art Conventionally, in a multi-stage automatic transmission mounted on a vehicle, a friction start system (starting clutch system) having no torque converter has been known.
In order to smoothly start the vehicle, a hydraulic control for gradually engaging the clutch in accordance with the accelerator opening is performed. [0003] However, in an automatic transmission having a forward clutch and a reverse clutch,
When starting clutch control is performed for these clutches,
It is necessary to provide a control mechanism for controlling the starting clutch for each of the two clutches. There are also two lubrication circuits that supply a large amount of lubricating oil to these clutches during clutch control operation to prevent burning and a small amount of lubricating oil during clutch disengagement to prevent dragging. Must be provided. As described above, the conventional automatic transmission has a problem that the device is complicated and the manufacturing cost is high. An object of the present invention is to provide an automatic transmission that has a simple structure and can be manufactured at low cost by using one friction element as a starting clutch. [0005] To achieve this object, an automatic transmission according to claim 1 has a first gear train having a simple planetary mechanism and forming a two-speed shift;
The present invention is directed to a configuration in which a multi-speed shift is formed by combining a second gear train having a forward clutch and a reverse clutch and forming three or more shift speeds, and in particular, one of friction elements provided in the first gear train. And a control means for operating the one as a starting clutch. Therefore, when the position of the shift lever is switched from the N range to the D range or the R range by the driver, the control means controls any one of a clutch and a brake as a friction element included in the first gear train. Is operated as a starting clutch. Therefore, in the configuration of the conventional automatic transmission in which the forward clutch and the reverse clutch are operated as the starting clutch, it is necessary to provide control means for operating each of the two clutches as the starting clutch. In the automatic transmission according to the first aspect, since only the control means for one friction element needs to be provided, the control means such as the hydraulic control circuit can have a very simple structure. Further, for the clutch that operates as a starting clutch, a lubrication circuit is provided that supplies a large flow of lubricating oil to prevent burning during clutch control operation and supplies a small flow of lubricating oil to prevent dragging during clutch disengagement. In some cases,
Since only one lubrication circuit needs to be provided, the lubrication circuit can have a simple structure. As a result, the automatic transmission can be manufactured at lower cost. An embodiment of an automatic transmission embodying the present invention will be described below with reference to the drawings. The automatic transmission 1 is an automatic transmission of four forward speeds and one reverse speed employing a friction start system (starting clutch system) having no torque converter. The automatic transmission 1 includes, as shown in the gear train diagram of FIG. 1, an input shaft 7 to which a torque from the engine is input,
The first shaft is connected to the input shaft 7 and forms a one-to-two speed shift.
A gear train 3, a second gear train 5 to which rotation output from the first gear train 3 is transmitted to form a three- to four-speed shift, and an output provided parallel to the input shaft 7 and connected to the second gear train 5 And a shaft 9. The first gear train 3 includes a set of simple planetary mechanisms 3a, and a pinion gear P1 connected to the input shaft 7, a ring gear R1 externally meshed with the pinion gear P1, and an internal gear meshed with the pinion gear P1. The vehicle includes a sun gear S1 and a carrier CA1 that rotatably supports the pinion gear P1. Also, the carrier CA1
And the sun gear S1 are connected via a clutch C0. Further, the sun gear S1 is connected to the automatic transmission case 19 via the brake B0, and the carrier CA1 is connected to the automatic transmission case 1 via the clutch C0 and the brake B0.
9. On the other hand, the second gear train 5 is composed of two sets of planetary gears, a front planetary gear 5a and a rear planetary gear 5b. The front planetary gear 5a includes a pinion gear P2, a ring gear R2 externally meshed with the pinion gear P2, a sun gear S2 internally meshed with the pinion gear P2, and a carrier CA2 rotatably supporting the pinion gear P2. The carrier CA2 is connected to the automatic transmission case 19 via the brake B3. Further, the sun gear S2 is connected to the automatic transmission case 19 via the brake B1, and is connected to the output of the first gear train 3 via the clutch C2, so that rotation from the first gear train 3 is transmitted. The ring gear R2 is connected to the output shaft 9
It is connected to the. The rear planetary gear 5b includes a pinion gear P3, a ring gear R3 that externally meshes with the pinion gear P3, and a sun gear S that internally meshes with the pinion gear P3.
3 and a carrier CA3 that rotatably supports the pinion gear P3. The carrier CA3 is connected to the output shaft 9. Further, the sun gear S3 is connected to the brake B1.
Is connected to the automatic transmission case 19 through the clutch C
2 is connected to the output of the first gear train 3
The rotation from the gear train 3 is transmitted. Further, the ring gear R3 is connected to the output of the first gear train 3 via the clutch C1, and the rotation from the first gear train 3 is transmitted. FIG. 2 graphically shows the shift speeds achieved by the engagement and release of each clutch and brake (indicated by the symbol “○” and the symbol “−”). As can be seen with reference to FIG. 2, the first speed is achieved by the engagement of the clutch C0, the clutch C1, and the brake B3. The second speed is achieved by engagement of the clutch C0, the clutch C1, and the brake B1. The third speed is achieved by engagement of the clutch C0, the clutch C1, and the clutch C2. The fourth speed is achieved by engagement of the brake B0, the clutch C1, and the clutch C2. On the other hand, reverse (REV) is achieved by engagement of the clutch C0, the clutch C2, and the brake B3. As shown in FIG. 1, the clutches C0, C1, C2 and the brakes B0, B1, B3 are connected to a hydraulic control circuit 11 via oil passages 11a (shown by broken lines). These clutches and brakes are used to select a range by the driver's shift lever 15,
It is configured to be operated by the hydraulic pressure supplied from the hydraulic control circuit 11 according to the accelerator opening that changes according to the amount of depression of the accelerator 13 and the gear position determined by the vehicle speed detected by the vehicle speed sensor 17. Clutch C0
Especially, since the hydraulic control circuit 11 functions as a starting clutch in the automatic transmission 1, the hydraulic control circuit 11 is configured to perform a starting clutch control for engaging the clutch C0 while gradually sliding according to the accelerator opening. Have been.
The hydraulic control circuit 11 is configured by combining a well-known oil pump, a valve, a solenoid, and the like. In the automatic transmission 1 having such a configuration, when the position of the shift lever is switched from the N range to the D range or the R range by the driver, the hydraulic control circuit 11 is included in the first gear train 3. The clutch C0 is operated as a starting clutch, and the accelerator 1
Control is performed such that the engagement is gradually performed in accordance with the opening degree of No. 3. Here, the clutch C0 corresponds to a friction element of the present invention, the hydraulic control circuit 11 corresponds to control means, the clutch C1 corresponds to a forward clutch, and the clutch C2 corresponds to a reverse clutch. As described above, according to the automatic transmission 1 of the present embodiment, the hydraulic control circuit 11 controls the first gear train 3
Is controlled so that the clutch C0 operates as the starting clutch. Therefore, the clutch C1 as the forward clutch and the clutch C2 as the reverse clutch
The hydraulic control circuit 11 can have an extremely simple structure as compared with a configuration in which each of the two clutches operates as a starting clutch, and the automatic transmission 1 can be manufactured at low cost. Further, a lubricating circuit for supplying a large amount of lubricating oil to the starting clutch during control operation to prevent burning and a small amount of lubricating oil during release to prevent dragging is provided. However, in the above embodiment, only one lubrication circuit for the clutch C0 as the starting clutch need be provided. Therefore, the lubrication circuit can be configured to be extremely simple compared to a configuration in which a lubrication circuit for the clutch C1 as a forward clutch and a lubrication circuit for the clutch C2 as a reverse clutch are provided. As a result, the automatic transmission 1 can be manufactured at low cost. Note that the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention. For example, in the above embodiment, the simple planetary mechanism 3a is an overdrive mechanism, but may be constituted by an underdrive mechanism. FIG. 3 shows a first gear train 3 as a modification of the first gear train 3.
0 is a gear train diagram of FIG. The first gear train 30 is
A ring gear R1 'connected to the input shaft 7, a pinion gear P1' internally meshed with the ring gear R1 ', and a sun gear S1' internally meshed with the pinion gear P1 '. CA1 'rotatably supporting the pinion gear P1'
And Also, the carrier CA1 'and the sun gear S1'
Are connected via a clutch C0 'and to a second gear train (not shown). Furthermore,
The sun gear S1 'is connected to the automatic transmission case 19 via a brake B0', and the carrier CA1 'is connected to the automatic transmission case 1 via a clutch C0' and a brake B0 '.
9. In this modification, the brake B
0 'corresponds to the friction element of the present invention operated as the transmission clutch. Further, in the above embodiment, the simple planetary mechanism 3a is provided on the input shaft 7 side, but it may be provided on the output shaft 9 side. The above-described embodiment is merely an example, and it is needless to say that the above-described embodiment can be appropriately modified and implemented according to the application. As described above, according to the automatic transmission according to the first aspect of the present invention, in the configuration of the conventional automatic transmission in which the forward clutch and the reverse clutch operate as the starting clutch, Although it is necessary to provide control means for operating each of the two clutches as a starting clutch, the automatic transmission according to claim 1 requires only control means for one friction element. This has the effect that the control means such as a circuit can have a very simple structure. Further, for the clutch that operates as a starting clutch, a lubrication circuit is provided that supplies a large flow of lubricating oil to prevent burning during clutch control operation and supplies a small flow of lubricating oil to prevent dragging during clutch disengagement. Also in this case, since only one lubrication circuit needs to be provided, the lubrication circuit can have a simple structure. In addition, as a result, there is an effect that the automatic transmission can be manufactured at lower cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a gear train diagram showing a configuration of an automatic transmission according to an embodiment to which the present invention is applied. FIG. 2 is a table showing a correspondence between a shift speed and an operation state of each clutch. FIG. 3 is a gear train diagram showing a modification of the first gear train. [Description of Signs] 1 Automatic transmission 3 First gear train 3a Simple planetary mechanism 5 Second gear train 7 Input shaft 9 Output shaft 11 Hydraulic control circuit 30 First gear train 30a Simple planetary mechanism C0 Clutch B0 'Brake

Claims (1)

Claims: 1. A combination of a first gear train having a simple planetary mechanism and forming a two-speed shift, and a second gear train having a forward clutch and a reverse clutch and forming a three-speed or more shift. An automatic transmission configured to form a multi-speed transmission, comprising: control means for operating one of friction elements provided in the first gear train as a starting clutch.